Nutritional regulation of adipocyte differentiation in animals

The incidence of obesity has increased in the U.S. until an obesity epidemic now exists. American consumers are acutely aware of the consequences of obesity and are increasingly associating the consumption of high-fat foods with having a negative impact upon their health. This has in turn forced producers to grow leaner animals. Since excess fat is an undesired commodity, the need to understand mechanisms that regulate adipose tissue differentiation has never been more important. Understanding the underlying regulation of adipogenesis is a vital first step toward developing strategies that limit fat accretion in growing animals. The resulting increase in consumer demand and improved productive efficiency associated with such technologies should ensure that the animal industry will remain solvent in the years to come. However, despite a great deal of effort directed at elucidating the regulation of adipogenesis during the last decade, our understanding of adipose tissue growth and development in agriculturally important animals remains very limited. This study used a porcine stromal-vascular cell primary culture system to study the nutritional regulation of adipogenesis. Specifically, the underlying molecular mechanism governing the anti-adipogenic actions of retinoic acid and conjugated linoleic acids was investigated. Retinoic acid inhibited the differentiation of pig preadipocytes through activating the RARa receptor and inhibiting the expression of the key adipogenic transcription factors PPARy and ADD1 while simultaneously increasing the expression of COUP-TF. Conjugated linoleic acids inhibited the differentiation of pig preadipocytes in an isomer-specific fashion via a mechanism that also involved reduced expression of PPARy and ADD 1 and the increase of COUP-TF message abundance. Importantly, C/EBPa and β expression was unaffected in either study. Finally, feeding retinoic acid to growing broilers at levels 32 times greater than the minimum NRC requirements tested the hypothesis that retinoic acid is a potent inhibitor of adipogenesis. Feeding retinoic acid decreased total carcass lipid by 14% and abdominal fat mass by 10%. However, abdominal fat retinoic acid levels were unaltered by the diet suggesting that a physiological mechanism exists in the chicken which prevented retinoic acid from accumulating in adipose tissue and may have limited the response to supplementing the diet with retinoic acid

New Insights on the Mobility of Viral and Host Non-Coding RNAs Reveal Extracellular Vesicles as Intriguing Candidate Antiviral Targets

Intercellular communication occurring by cell-to-cell contacts and via secreted messengers trafficked through extracellular vehicles is critical for regulating biological functions of multicellular organisms. Recent research has revealed that non-coding RNAs can be found in extracellular vesicles consistent with a functional importance of these molecular vehicles in virus propagation and suggesting that these essential membrane-bound bodies can be highjacked by viruses to promote disease pathogenesis. Newly emerging evidence that coronaviruses generate non-coding RNAs and use extracellular vesicles to facilitate viral pathogenicity may have important implications for the development of effective strategies to combat COVID-19, a disease caused by infection with the novel coronavirus, SARS-CoV-2. This article provides a short overview of our current understanding of the interactions between non-coding RNAs and extracellular vesicles and highlights recent research which supports these interactions as potential therapeutic targets in the development of novel antiviral therapies

Validation of the Residual Feed Intake Model in Brangus Heifers: Determination of the Optimal Days on Feed Interval to Estimate Dry Matter Intake and Average Daily Gain

Brangus cattle are gaining popularity in the Southeast U.S. due to the desirable heat tolerance from their Brahman influence combined with the superior carcass merit aspects of Angus genetics. However, little is known about the optimal evaluation conditions for this hybrid breed when placed on test for Residual Feed Intake (RFI), a heritable measure of feed efficiency that allows improvement in performance without altering carcass traits. To address this, dry matter intake (DMI) was measured on Brangus heifers for 70-d to determine the optimal days on feed required to estimate feed intake and ADG and assess if inclusion of ultrasound measures of carcass merit into the model impact RFI rankings for this breed. The 56-d test period had a regression coefficient of 0.96 (p 2 = 0.94, rp = 0.97 (p p < 0.0001), indicating little change in rank of cattle for DMI compared to a 70-d test. ADG was the limiting factor in determining test duration. Based upon examining only heifers that calved, ultrasound backfat measures should be included in the RFI model to normalize for differences in heifer maturity. Results from this study indicate that a test duration of 56-d is sufficient to accurately estimate DMI in this population. This data indicates on-test duration can be shortened, enhancing the rate of genetic change by reducing cost and increasing the number of animals that can be tested annually

Sampling Adipose and Muscle Tissue following Post-Harvest Scalding Does Not Affect RNA Integrity or Real-Time PCR Results in Market Weight Yorkshire Pigs

Improving production efficiency while enhancing pork quality is pivotal for strengthening sustainable pork production. Being able to study both gene expression and indices of pork quality from the same anatomical location of an individual animal would better enable research conducted to study relationships between animal growth and carcass merit. To facilitate gene expression studies, adipose and muscle tissue samples are often collected immediately following exsanguination to maximize RNA integrity, which is a primary determinant of the sensitivity of RNA-based assays, such as real-time PCR. However, collecting soft tissue samples requires cutting through the hide or skin. This leaves the underlying tissue exposed during scalding, poses possible food safety issues, and potentially confounds pork quality measures. To overcome these limitations, the effect of tissue sample timing post-harvest on RNA integrity, real-time PCR results, and pork quality measurements was investigated by sampling subcutaneous adipose tissue and longissimus thoracis et lumborum muscle immediately following either exsanguination, scalding, or chilling. Sampling time did not affect RNA quality, as determined by the RNA integrity number of RNA samples purified from either adipose (RIN; p > 0.54) or muscle tissue (p > 0.43). Likewise, the sampling time did not influence the results of real-time PCR analysis of gene expression when comparing RNA samples prepared from adipose or muscle tissue immediately following either exsanguination or scalding (p > 0.92). However, sampling tissue prior to scalding resulted in a greater visual color score (p L* (p b* (p p < 0.41). These results suggested that if both RNA-based assays and meat quality endpoints are to be performed at the same anatomical location on an animal, tissue sampling to facilitate RNA-based assays should occur at a time point immediately following scalding. These findings demonstrated that sampling of adipose and muscle tissue can be delayed until after scalding/dehairing without decreasing the RNA integrity or altering the results of real-time PCR assays, while doing so was associated with little impact on measures of pork quality

Characterization of Growth Performance, Pork Quality, and Body Composition in Mangalica Pigs

European heritage breeds, such as the Blonde (B), Red (R), and Swallow-bellied (SB) Mangalica pig, display an extreme propensity to fatten and are reputed to produce superior quality pork. This suggests that Mangalica pork should command a higher price, and the Mangalica is a candidate breed to target niche markets within the United States. Our objectives were to test this hypothesis by (1) directly comparing growth performance and carcass merit of purebred Yorkshire (Y), B, R, and SB Mangalica pigs to identify the best breed for adoption, and (2) comparing indices of pork quality in purebred R, Y, and crossbred (R &times; Y) pigs to determine if crossbreeding represented a viable alternative to the adoption of purebred Mangalica. Daily feed intake, average daily gain (ADG), and feed efficiency were highest in Y and lowest in SB pigs with B and R ranked intermediately (p &lt; 0.001). Backfat thickness was greatest in B and lowest in Y with R and SB ranked intermediately (p &lt; 0.001). Marbling score was greatest in R pigs and lowest in Y pigs with B and SB ranked intermediately (p &lt; 0.01). In contrast, loin eye area (LEA) was greatest in Y pigs compared to B, R, and SB (p &lt; 0.001). Indices of meat quality were then compared in R, R &times; Y, and Y pigs. Backfat thickness and marbling scores were greater in R than R &times; Y and Y pigs (p &lt; 0.001) while LEA was greater in Y than R &times; Y and R pigs (p &lt; 0.001). Loin and ham ultimate pH, color, and firmness scores were significantly greater in R than R &times; Y or Y pigs (p &lt; 0.05). Meanwhile, cook loss was significantly less in R than Y pigs (p &lt; 0.007) while Warner-Bratzler Shear Force (WBS) was not different in chops between groups (p &lt; 0.11). These data indicate that though Mangalica exhibit poorer growth performance, Mangalica pork exhibits superior pork quality attributes, suggesting that higher price points for Mangalica pork in niche markets are justified

Determination of Optimal Harvest Weight for Mangalica Pigs Using a Serial Harvest Approach to Measure Growth Performance and Carcass Characteristics

Mangalica pigs are a popular niche breed given their reputation for superior pork quality. However, growth and carcass parameters for this breed are poorly documented. To better characterize optimal harvest weights for the Mangalica, a growth trial was conducted whereby pigs (n = 56) were randomly distributed across stratified harvest weights (50, 57, 68, 82, 93, 102, 127 kg) in a completely randomized design. Pigs were fed standard finisher rations with individual daily feed intakes and weekly body weights recorded for all animals. At 24 h postmortem, carcasses were split and ribbed with marbling and loin eye area (LEA) measured at the 10th rib. Primal cuts were fabricated and individually weighed. Fat back was separated from the loin and weighed. As expected, live weight significantly increased across the weight class (p &lt; 0.0001). ADG was similar across classes up to 82 kg live weight, before steadily declining with increasing weight class (p &lt; 0.0025). Likewise, feed efficiency did not differ between classes until weights heavier than 82 kg (p &lt; 0.03). LEA significantly increased by class up to 82 kg and then plateaued as harvest weight increased further (p &lt; 0.003). Marbling score significantly increased with increasing weight class up to 102 kg, where they then plateaued (p &lt; 0.04). Fat back dramatically increased across all weight classes (p &lt; 0.0001) despite negligible increases in LEA or marbling after 102 kg. Primal cut weights for the ham (p &lt; 0.0001), loin (p &lt; 0.0001), Boston butt (p &lt; 0.0001), shoulder (p &lt; 0.0001), and belly (p &lt; 0.0001) all significantly increased with increasing live weight though significant fat deposition contributed to this gain. These data suggest an optimal harvest weight occurs between 82 to 102 kg, while offering little objective justification for harvesting Mangalica pigs at heavier live weights

Distribution and regulation of gonadotropin-releasing hormone, kisspeptin, RF-amide related peptide-3, and dynorphin in the bovine hypothalamus

Recent work has led to the hypothesis that kisspeptin/neurokinin B/dynorphin (KNDy) neurons in the arcuate nucleus (ARC) play a key role in gonadotropin-releasing hormone (GnRH) pulse generation and gonadal steroid feedback, with kisspeptin driving GnRH release and neurokinin B and dynorphin acting as pulse start and stop signals, respectively. A separate cell group, expressing RFamide-related peptide-3 (RFRP-3) has been shown to be a primary inhibitor of GnRH release. Very little is known regarding these cell groups in the bovine. In this study, we examined the relative immunoreactivity of kisspeptin, dynorphin, and RFRP-3 and their possible connectivity to GnRH neurons in the hypothalami of periestrus and diestrus bovine. While GnRH and RFRP-3 immunoreactivity were unchanged, kisspeptin and dynorphin immunoreactivity levels varied in relation to plasma progesterone concentrations and estrous status. Animals with higher plasma progesterone concentrations in diestrus had lower kisspeptin and increased dynorphin immunoreactivity in the ARC. The percentage of GnRH cells with kisspeptin or RFRP-3 fibers in close apposition did not differ between estrous stages. However, the proportions of GnRH cells with kisspeptin or RFRP-3 contacts (∼49.8% and ∼31.3%, respectively) suggest direct communication between kisspeptin and RFRP-3 cells to GnRH cells in the bovine. The data produced in this work support roles for kisspeptin and dynorphin, within the KNDy neural network, in controlling GnRH release over the ovarian cycle and conveying progesterone-negative feedback onto GnRH neurons in the bovine

Surface Color Variations of Ground Beef Packaged Using Enhanced, Recycle Ready, or Standard Barrier Vacuum Films

With current meat industry efforts focused on improving environmental influencers, adopting sustainable packaging materials may be an easier transition to addressing the sustainability demands of the meat consumer. With the growing popularity of vacuum-packaged meat products, the current study evaluated instrumental surface color on fresh ground beef using vacuum packaging films, recycle-ready film (RRF), standard barrier (STB) and enhanced barrier (ENB). Ground beef packaged using ENB barrier film was lighter (L*), redder (a*) and more vivid (chroma) than all other packaging treatments during the simulated display period (p &lt; 0.05). By day 12 of the simulated retail display, the ground beef surface color became lighter (L*), more yellow (b*), less red (a*), less vivid (chroma) and contained greater forms of calculated metmyoglobin, oxymyoglobin (p &lt; 0.05). The current results suggest that barrier properties of vacuum packaging film for ground beef are pivotal for extending the surface color during fresh shelf-life conditions